Electronic part mounting machines use electronic part adsorbing or suction holding nozzles for adsorbing required electronic parts and mounting them at predetermined locations on circuit boards.
Used as a known electronic part adsorbing nozzle is a nozzle made of a super hard metal, in which a tip thereof has a nozzle opening formed in a predetermined shape and an adsorbing surface coated with diamond for imparting abrasion resistance and a magnetization-preventive function.
The nozzle opening mentioned above consists, for example, of a center slit and "V-shaped" slits extending from the middle of the center slit symmetrically rightward and leftward, and formed symmetrical with regard to a vertical center axis and a horizontal center axis respectively of the adsorbing surface. Owing to this shape, the nozzle opening is configured so as to have adsorbing portions for exerting an adsorbing force to an electronic part and supporting portions for receiving the electronic part, which portions are distributed alternately and uniformly so that the nozzle can cope with variations in size and deviations in locations of electronic parts.
However, the known electronic part adsorbing nozzle having the configuration described above poses problems which are described below:
The known electronic part adsorbing nozzle is often threatened to be defective, and inevitably requires a high manufacturing cost due to low yield since the coating material often protrudes into the nozzle opening at a stage to coat the adsorbing surface of the tip with diamond.
Further, the known adsorbing nozzle poses a problem from a viewpoint of compressive resistance since the nozzle opening is composed of the radially formed "V-shaped" slits, the supporting portions naturally have acute angles in an adsorbing condition and tips of the portions having the acute angles are liable to be broken. This problem will be described more concretely. When an electronic part which has an area smaller than a half of the nozzle opening is adsorbed, an adsorbing force is exerted to the electronic part only within a central region of the nozzle opening, the adsorbing force exerting to the electronic part is received by the supporting portions having the acute angles and a stronger compressive force is loaded on the supporting portions having the acute angles at a stage to mount the electronic part onto a circuit board, whereby the supporting portions having the acute angles located at the tip of the nozzle are liable to be broken.
Furthermore, the known electronic part adsorbing nozzle poses another problem that it is obliged to be disposed of when its tip becomes defective since the nozzle is formed as an integral part ranging from its tip having the diamond coating to a mounting shank (grip) and the nozzle cannot be repaired simply by replacing the nozzle tip with a new one when it is broken.